Orthopaedic devices are used in the treatment of many injuries or conditions. For example, treatment of certain bone fractures involves stabilizing selected portions and/or fragments of bone using an implantable orthopaedic plate and/or an implantable orthopaedic nail, and various bone screws or pins. As another example, joints can be fused or otherwise immobilized using plates and/or nails secured with bone screws or pins.
In some instances, it is necessary or beneficial to target a hidden landmark of an orthopaedic implant. For example, some procedures involve placement of bone screws or pins through selected apertures of an implanted orthopaedic device. Such targeting can be accomplished in some cases using radiographic imaging. Unfortunately, radiographic imaging can be undesirable for various reasons. For example, exposure to radiation energy used in the imaging process can be harmful to a patient as well as to those treating the patient or assisting those treating the patient. Additionally, radiographic imaging can be expensive and time-consuming, as well as potentially inaccurate, or less accurate than desired.
Recent advances have seen an increase in the use of landmarks such as slotted holes and combination holes in bone plates and nails. These so-called combination holes, can include a partially-threaded portion and a non-threaded portion that is used for compression of the bone in a particular direction. Drill guides or other mechanical targeting devices have been used for targeting different hole positions within these combination holes, but these methods can be time consuming and difficult for surgeons to manipulate the mechanical targeting devices during surgery.
Recently, electromagnetic-based targeting of orthopaedic implants has been employed to determine relative locations and orientations of tools and features, such as landmarks, of an implanted orthopaedic device. For example, distal locking holes of an implanted intramedullary nail can be targeted for drilling and fixation using a locking screw with an electromagnetic targeting system, such as the TRIGEN® SURESHOT® distal targeting system offered by SMITH & NEPHEW®. However, these targeting systems have not been used for targeting multiple hole locations within, for example, a combination or slotted hole, to allow surgeons to achieve optimal positioning of bone screws or pins for controlled compression of a bone fracture.